Field of the Disclosure
The present disclosure relates generally to video image processing and in one exemplary aspect, to methods and apparatus for the storage and/or subsequent provision of overlapping regions of imaging data for the generation of optimized stitched images.
Description of Related Art
Spherical images are typically obtained by capturing multiple images with overlapping fields of view from different cameras and combining (“stitching”) these images together in order to provide a two-dimensional projection. Conventional stitching algorithms may result in undesirable artifacts, including around the stitch lines, due to imperfections in the stitching process.
Different electronics devices may have different mobility, computational capabilities, display capabilities, power limitations, and/or other operational considerations. For example, a consumer device such as a mobile phone or multi-camera capture device may be convenient to capture source photographs during an outdoor activity, and/or quickly view a roughly stitched image, however it may lack the computational power to perform high quality stitching. Similarly, while a laptop or tower computer may have more than adequate compute power to perform high quality stitching, they are poorly suited to outdoor activities.
Unfortunately, existing image capture techniques and rendering formats “fix” a stitched image to a particular quality. For example, when a mobile device quickly stitches an image from multiple source images, the resulting stitched image cannot be re-stitched on a more capable machine; it is locked into the quality of the mobile device (which may be relatively poor).
Additionally, storing post-stitch data with the original source images may not always be feasible due to e.g., storage considerations.
Furthermore, observable quality is highly subjective and the user may be willing to accept a quickly stitched version with limited augmentation to a higher stitch quality. In some cases, this may even be limited to spatial regions of the same image or time regions of the same video stream.
Moreover, prior art techniques assume a particular projection (e.g., equirectangular (cylindrical), cubic, octahedral, and/or spherical projection) for stitching images (e.g., for so-called virtual reality (VR) content). Once an image has been stitched according to a first projection, the image cannot be changed to a different projection. Instead, if a different projection is desired, the source images must be re-stitched from scratch according to the new projection.
To these ends, techniques are needed to improve upon these conventional stitching algorithms. Moreover, improvements are needed to improve compression efficiencies associated with the transmission and storage of stitched images in order to, inter alia, more efficiently leverage the capabilities of rendering platforms and/or viewing applications, regardless of the original source images.